Mass air meter question
 

My 95 S320 is starting to develop a very slightly rough idle, and also it's been shifting kind of funky. The engine has been slowly losing power. I'm thinking that the mass air meter is the problem. To clean it, can I just use regular brake clean, or should I use electronic parts cleaner??

electric parts cleaner or specific MAFS cleaner (e.g. CRC brand - in the US, these sell for ~$6 at autoparts stores here). I wouldn't use brake cleaner.. that's some strong stuff.

I used the CRC Cleaner this past weekend. I suppose it works on very sensitive parts, but I noticed when I accidently sprayed a bit on a slightly dirty part of my index finger, the dirt was still there.

I think if you have the wire sensor, which will burn off residue, you can get away with a harsher cleaner. If you have the flat film sensor, which I have, you don;t want any residue left behind.

HFM/SFI do not have a Hot Wire MAF system.

so, it's the film type of sensor?? Is the cmc electronics cleaner ok to use arthur?? That seems to be all I can get locally...

Your finger and the sensor are made of different materials ;) I would venture a guess that the dirt "clings" differently to the sensor from your skin, and the cleaner itself has various chemicals which have different effects when encountering your skin.

amosfella, aren't there any car-parts stores near you?

<so, it's the film type of sensor??>
That what I said...HFM is "Hot Film Mas".
If it were a wire sensor, it would be LH/SFI. That would be the V8 system.

CRC MAS/MAF spray cleaner.

I know, but I still can;t help but wonder... Also, it is guaranteed residue-free, but it left plenty of white spots on the intake pipe, manifold and valve cover (from overspray) when I used it in those areas. That sounds like "residue" to me. (Brake cleaner never did that). But I'm sure it worked OK on the sensor.

LOL... I'm glad I walked into the store in town. The guy coudln't see what was right under his nose. They had air mass sensor cleaner there.
There is one auto parts store within 60 miles to me...

I believe that car has OBDII. So I would think it would throw a code if the MAF was that bad. I assume the CEL is not on?

Attempting to clean the MAF on our 95 E320 was an exercise in frustration. Replacement was the cure.

Jim

Didn't work for me either. But I had a code. The old P0170.

I haven't checked for a code, but I cleaned out the AMS, took the negative off the battery for 15 seconds, and put it back on. Then i started the car, and let it run while I checked and adjusted the tire air pressure. The engine was definitely running smoother. The transmission wasn't acting up, or shifting hard either when I took it for a drive. The engine felt like it had a lot more power.
As for OBD2, I have the part under the dash, but I don't have a reader. Can one read the codes from the engine on OBD2, Arthur??
I don't need the mercedes specific one. Looking through waxed paper works for me for now.... :DI was looking at maybe buying the star diagnostic system from a guy in quebec for $700. Didn't include the laptop though....

You have been asked a diagnostic question...
Do you have a CE LAMP Iluminated ?????????????????????????????????????

How so? All I needed to do was disconnect the tube behind the air filter box, spray the sensor, then put it back.

I think he means it didn't fix it.

Interesting. I've only had experience cleaning "young" MAFS that aren't too dirty. I'm afraid to use brake cleaner, as I've seen what it can do to paint - I know I know, paint is different material from the sensor... "but I still can't help but wonder..." :p :D

Residue is one reason to be careful of some electrical cleaners, as they may carry "lubricating" material, if one doesn't read the label carefully!

no, the check engine light isn't on. nor was it on. I shoudl go and see if that bulb even works. The idle, and tranny shifting did smooth out.... Maybe I"m just hypersensitive and noticed it while it was still in spec....

Since Arthur is paying attention I will ask this:

Does disconnecting the battery reset the adaptations to 0 or just reset trouble codes, or both?

Noting that the check engine light isn't on is meaningful information only if it works.

Ok

Next test is to turn key to Run position and see if you have a CE lamp [ do not start car]

If yes, then you can still get cdes from the 38 pin DM with a Led Tool.
If no, then you can't

Is car a Cnd version???

When that car wasn't running, I turned the key to the ON position. The light didn't illuminate... Does this mean the bulb is burned out?? Or does this mean that there is no problem??
I have always tried to let my instincts tell me if something is wrong. I don't rely on technology, but find it useful at times to let me know...

Car is a canadian version. Without the check engine light being on with the key in the on or run position, does that mean there are no codes to read??

It means you have no CE b/c ytou have no N/59 module or bad bulb..that is what we are tryting to determine , but you have to answer the questions.
The ??????????????? is " Is the car CND version.???? "..Yes/No

car is Canadian version.

<<Please see above post..... >

Yeah...ya know, when you get someone to answer , it would benefit you to answer the questions in RESPONCE...

So , the Reason for my Cnd ? was you don't have a CE cuz you don't have a N/59 DM [ Diagnostic Module.]

By disconnect, you have reset the ECU Memory to mean, so that means you may have a condition that will come back..the suspect would be FP reg or Vac leak.

If the Maf was bad, I would nor expect instant remedy by simply reset.
Drive it and if the condition repeats, then get codes.....

http://www.geocities.com/MotorCity/Downs/1039/mercedes/cs1000_mb.pdf

Sorry, Arthur, I shouldn't have been rude.... I appreciate your help.... Without the N/59 DM, does that mean that I cannot use the LED blinker tester??
What's a FP reg??

Would an OBD2 code reader diagnose the engine problems in that car?? The port that's under the dash??

Go to that site I posted and look your chassis up for code info.
The FP reg [ fuel pressure] has a vac hose On it..pull the hose and see if any fuel is evident in hose or FP port..if yes , replace it.
And lok for vac leaks.

Unmetered fuel OR intake air will screw up the adaptation and the Maf can not correct for it cuz it is unmetered. So, you thi9nk that the maf is bad, but that may bot be the case if you have a vac leak or FP reg is leaking fuel into the intake...and since those two are very common on 104 HFM systems and take 5 min to check, that is what I would do of I were you.

Where is the fuel pressure regulator on that car?? Also, what is the best place to pull a vacuum from to check for vac leaks??

Does that mean the adaptations are reset? Even transmission adaptations (if a car had them)?

Never mind. I found it. There is no sign of gas in the regulator or vac line. When I tried to pull a vacuum on the vac line with a hand pump, it wouldn't hold anything at all. The vacuum was gone before the handle was fully released.... I didn't check any further as it's dark out. I'll look at any suggestions in the morning.

You need to pull the vacuum on the regulator. Not sure if that is what you meant.

I"ll pull a vac on the reg tomorrow morning.

You don't Pull a vac on anything...you are looking for a vac leak at a line or connection.
I already told you how to test the regulator and it has passed the test. It leaks gas out the port into the vac line , which the engine then sucks in raw, unmetered fuel which the engine management can not control.
A ruptured reg also can no longer control the fuel rail pressure to spec, so the a/f mixture is also off.

Common vac hose leaks on HFM engines are at the SOV valves for both the AIR system and the EGR system, along with the Purge valve..that is why you want codes...........................first check is the plastic line under the frint cover...they carck all the time on that engine.

And none of this means you do not have a bad Maf, it is just things to check first ...getting codes will help in your diagnosis.

I built a LED type blinker code thingy... Which pins, and how are they numbered??
By under the front cover, you mean under the black plastic cover on the front of the engine??

Front engine cover. It lifts up to expose the vac lines and SOV valves that are common leak problems.
The codes are in that site I posted for you.
The pins #s are on page 12 ...your car should have that 38 connector ....does it ?
Also go to page 31/34..the pins i would be loking at right off would be 19 and 4.
Your chassis is 140.032 with engine 104.994. That will be a HFM/SFI system , but being from Cnd, I don't know if it the same as US FED version...b/c it has NO CE , then it is NOT Cal version and has no N/59 module.
See if you have that plug on page 12.

I'll assume by front engine cover, you mean the black plastic cover on the top front of the engine...
Chassis is actually 140.033.
Yes, it has the 38 pin connector inside the box behind the firewall on the right hand side. I do have the plug on page 12.

<Chassis is actually 140.033. >

Same car w/LWB..

Why are you having so much trouble with the front engine cover ...pull it off and get to the vac lines,

38 pin plug on page 12 is correct , so , again... just go to that site I posted and you will see all the codes for your model and what pins to use.
I am not versed on all Cnd mandates , so you wiill have to punt on the exactness as the site is for US versions.
That is all I can tell you.

I didn't see any leap problems. I pulled the connectors off, plugged the ends, and pulled a vac on them as well... No leaks...
Tried the code reader. I plugged it in. Black to 1 red to 3, and yellow to 4,8,19. I couldn't get a single blink from the led on any of them... I had tried to use it before, and I might have hooked up the black and red backwards. Would that fry the LED??

Until I get a code reader that's working, is there anything else I should be checking??

Yeah..check your code tool.

Just put the Bk -and Red + on a Battery and push the button..that will tell you if you have constructed the tool correctly.

I'll go check it out soon here. My internet wasn't allowing me to access the forums. Sorry for taking so long to respond.

It didn't light up.

Well, my thoughts on that is you did not follow the parts section of the instuctions... You will notice that the LED that I mentioned to use is a Radio Shack Led with a built-in resistor, thereby making the LED a 12 v led ..you prob used a standard LED , which requires a seperate dropping resistor to be added so it does not blow out... which will happen the very first time you use it.
The second possible is you have the led wiredBackwards ..Leds are POLARITY sensitive, meaning they do not work unless they are wired correctly [ pos/neg]...you can tell that by reversing the leads at the battery in the test I gave you and see if it lights then..if yes , you have it backass.
Have to read the stuff as it is posted b/c it is thought out .

Did you observe the LED polarity ???
Did you use a 12 volt LED ???

To both questions, yes. The LED had the same part number as you specified in your diagram, and the longer connector was the positive according to the package. I was very careful about that.
I think I hooked it up backwards the first time I tried it. Would that have blown out the LED?? Backwards in the socket I mean.

Possibly

try it both ways on the battery and if it does not light either way, it is done..........w/o the switch... b/c you could have a bad sw .

You can do the same test , but use the odd lead for the battery neg, and that will eliminate the switch from the test circuit.

Doesn't light up when the black and red are reversed either.... I tested off the odd lead as well... Nada.... I'll have to get a new LED the next time I'm in the city....
Dad just bought an OBD2 scanner. Would that work to check from the port under the dash by any chance??

I read the codes with the obd2 code reader. It gave me back three codes. They are:
P0306 I think that was from before I replaced the spark plugs and connectors.
P0193
P1633

I ran a test again with the OBD2 scanner after driving about 50 miles stopping and starting. 3 engine starts, ran the car up to about 90 miles an hour, hard acceleration, regular acceleration.... No new codes either in pending or in stored.... Should I figure that the problem is fixed for now??